For patients who undergo removal of adenomas, colorectal cancer mortality risk is increased for those who had high-risk adenomas removed and reduced for those who had low-risk adenomas removed, according to a study published in the New England Journal of Medicine.

Magnus Løberg, M.D., from the University of Oslo in Norway, and colleagues used linkage of the Cancer Registry and the Cause of Death Registry of Norway to examine colorectal cancer mortality among 40,826 patients who underwent colorectal adenoma removal from 1993 to 2007. The standardized incidence-based mortality ratios (SMRs) were calculated using comparison rates for the Norwegian population.

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During a median follow-up of 7.7 years through 2011, the researchers identified 1,273 patients with a diagnosis of colorectal cancer. Among patients who had had adenomas removed, 398 deaths were expected from colorectal cancer and 383 were observed, for an SMR of 0.96 (95 percent confidence interval, 0.87 to 1.06).

Among patients with high-risk adenomas, colorectal cancer mortality was increased (expected deaths, 209; observed deaths, 242; SMR, 1.16; 95 percent confidence interval, 1.02 to 1.31), while among patients with low-risk adenomas, colorectal cancer mortality was reduced (expected deaths, 189; observed deaths, 141; SMR, 0.75; 95 percent confidence interval, 0.63 to 0.88).

“Colorectal cancer mortality was lower among patients who had had low-risk adenomas removed and moderately higher among those who had had high-risk adenomas removed, as compared with the general population,” the authors write.

  1. Løberg, Magnus, MD, et al. “Long-Term Colorectal-Cancer Mortality after Adenoma Removal.” The New England Journal of Medicine. DOI: 10.1056/NEJMoa1315870. August 28, 2014.